1.      Marram grass Ammophila arenaria is quick to colonise dunes which have built up to avoid regular tidal inundation.  This species responds well to coverage by windblown sand; keeping pace with accretion and binding young dune systems together with extensive roots.  During periods of onshore winds and plentiful blown sand, build-up can occur rapidly.  The ‘Lincshore’beach nourishment scheme provides an artificial supply of sand to the Lincolnshire coast, with recent evidence of longshore drift down to Gibraltar Point. Information concerning the volume of nourishment sand, migrating to Gibraltar Point is presently unclear, but this may be a major factor in future dune- building/accretion.

2.  Whilst dune accretion is apparent, particularly in the formation of embryo dunes, there has been much erosion of apparently stabilising outer dune, possibly exarcebated by changing beach profiles and the southward migration of the Greenshank Creek outflow. Rising sea level, leading to ‘coastal squeeze’and an increase in storm events are significant factors of tidal erosion.  The Lyme Ridge (Compt 1/12/A) named after the good representation of Lyme Grass has been the subject of much erosion.  In 10 years, some 80 metres of this ridge have been washed away.  Its front edge comprises an eroded cliff of up to 2 metres with the bare roots of marram visible.

Fronting this ridge, the beach is often scoured of sand, with extensive clay exposures. Landward, beach and dune material has migrated over a previously developing saltmarsh in a ‘natural retreat’ situation.  With the loss of the northern section of Lyme Ridge, windblown sand is again feeding the seaward edge of the East Dunes in part.  Marram is likely to respond well in this scenario.  The yellow dunes play an important role in soft coastal defence by absorbing wave energy. Extensive root systems of marram help to bind the dunes together, and whilst frontal erosion may be widespread, marram enhances the rebuilding of the dunes, given favourable winds and provided the sediment supply is continued.  Conversely, where sea buckthorn has succeeded over marram, the frontal dunes seem less resistant to erosion by wave action because the scrub is shallow-  rooted.

3.  Stabilisation of yellow dunes has often been encouraged through the exclusion of the public, under the perception that erosion is a negative factor.  Under present levels of visitor use, areas of light erosion occur on semi- fixed dune and these are considered positive. Elsewhere, visitor pressure may be seen as advancing the loss of frontal dunes where already stressed by tidal erosion.

4.  Of the coastal lepidoptera, the shore wainscot Mythimna litoralis is locally scarce and dependant on marram.

5.  Of the birds that nest in the yellow dunes, the skylark is the most important.  This species is red- listed as a bird of conservation concern and is a target BAP species. Dense populations of meadow pipit also depend upon this habitat, particularly where contiguous with saltmarsh.

6.  As the yellow dunes become semi-fixed, colonisation by rabbits may occur, although populations are not as dense when compared to established grey dune. However, the actions of rabbits will influence the stability and sward structure over the feature.

7.  Sizeable outcrops of rosebay willowherb Epilobium angustifolium exist on some outer dunes.  This is recognised as a negative factor which impacts upon the natural development of the yellow dune and outcompetes the key dune vegetation.  This species is widely regarded as an alien; it’s value to locally occurring invertebrates appears to be low (possibly one monophagous Chrysomelid), but more information in this respect is required.

8.  The open sandy conditions between the marram tufts in these communities are important for invertebrates.  Notable amongst a range of aculeate hymenoptera is the red- tailed sand- wasp Ammophila sabulosa.  Specialist arachnids include Arctosia spirata and at some sites, this habitat is considered important for natterjack toads.  Sea holly Eryngium maritimum persists in this community, with a small number of plants on the Old Spit (compt 1/11/B), which has long been starved of windborn material and is eroding. However, there is encouraging evidence of seedlings on the Outer Ridge (Compt1/11/C).  Sea bindweed Calystegia sepium, also of regional significance was lost during erosion of the outer dunes (compt 1/12/B) in the late 1980’s and now only occurs north of the NNR at Seacroft. Polypody Polypodium vulgare occurs patchily in Compt 1/13, although may succumb to Hippophae scrub.

9.  From landward, the advance of colonising sea buckthorn may occur quickly across the yellow dunes once stabilisation has commenced.  Isolated patches of scrub in this feature, provide an important ecotone for inverrtebrates and birds.  However, much of the outer dune ridge system on the reserve already exhibits a dense sea buckthorn canopy, which has succeeded over the marram communities.  The series of dune ridges which interrupt the strip saltings are almost completely scrub-clad and a patchwork of marram and sea buckthorn scrub is exhibited on the dune ridge west of Greenshank Creek (compt 1/13 & 1/14).  All of these ridges are disjunct from sand supply which is vital for accretion and to perpetuate the marram communities in advance of the scrubline.  With the natural course of succession, further yellow dune would be lost under scrub without intervention.  A sequence of aerial photographs reveals that scrub growth was rapid through the 1950’s and 60’s, coincidental with lowest rabbit population following the outbreak of myxomatosis.